As discussed in detail in U.S. patent applications Ser. No. 08/979,432, filed Nov. 26, 1997 ("the '432 Application"), Ser. No. 09/168,265, filed Oct. 8, 1998 ("the '265 Application"), and Ser. No. 09/208,116, filed Dec. 9, 1998 ("the '116 Application") (collectively referred to herein as "the Previous Applications", each of these Previous Applications being incorporated herein by this reference), light transmission through one or more subwavelength-diameter apertures provided in a thin metal (i.e. conductive and opaque in the wavelength of interest) film can be greatly enhanced by arranging the holes in a periodic array and/or by providing a periodic surface topography on the metal film (surface features such as dimples or protrusions) in conjunction with the aperture(s). This enhancement, which can be as large as a factor of 1,000, occurs when light incident on the conductive film interacts resonantly with a surface plasmon mode.
The present invention is a light transmission apparatus wherein the light transmission efficiency is even further enhanced in comparison to previous optical transmission apparatus. In addition, the invention includes a novel near-field scanning microscope, a novel mask technology for sub-wavelength lithography, a wavelength-selective filter and light collecting device utilizing the improved enhanced light transmission apparatus.